Stroke is the third leading cause of death and the leading cause of adult disability in the United States. Approximately 400,000 individuals in the U.S. suffer a stroke every year. For those who survive, it is a major cause of long-term disability. It is estimated that only ten percent of those who survive a stroke are able to return to their previous activities without significant impairment. Forty percent of all individuals who suffer an acute stroke are disabled to the extent that they require special assistance. Of these, ten percent need institutional care.
Stroke is classified by its cause into two main types: ischemic and hemorrhagic. In ischemic stroke, which occurs in approximately ninety percent of strokes, a blood vessel becomes occluded, and the blood supply to part of the brain is totally or partially blocked. Ischemic stroke is usually caused by atherosclerosis (fatty lumps in the artery wall), embolism (obstruction of blood vessels by blood clots from elsewhere in the body), or microangiopathy (small artery disease, the occlusion of small cerebral vessels).
The middle cerebral artery (MCA) is the vessel most commonly responsible for ischemic stroke. Sites within the brain affected by occlusion of the MCA include the motor cortex, sensory cortex, and Wernicke's area. Resulting functional deficits include sensory deficits, aphasia, and paralysis.
Hemorrhagic stroke, on the other hand, occurs when a blood vessel in the brain bursts, spilling blood into the spaces surrounding the brain cells. Hemorrhagic strokes generally carry a greater risk of death and permanent disability than ischemic strokes. Causes of hemorrhagic stroke include hypertension, cerebral aneurysms, cerebral arteriosclerosis, head injury, congophilic angiopathy, congenital artery defects, and prematurity.
Physical disabilities that can result from stroke include, but are not limited to, paralysis, numbness, pressure sores, pneumonia, incontinence, coma, apraxia (inability to perform learned movements), difficulties carrying out daily activities, appetite loss, vision loss, and pain. Emotional problems resulting from stroke can result from direct damage to emotional centers in the brain or from frustration and difficulty adapting to new limitations. Post-stroke emotional disorders include anxiety, panic attacks, flat affect (failure to express emotions), mania, apathy, and psychosis.
It is estimated that thirty to fifty percent of stroke survivors suffer post-stroke depression, which is characterized by lethargy, irritability, sleep disturbances, lowered self esteem, and withdrawal. Post-stroke depression is often treated with antidepressant drugs, which can present a risk of abuse or addiction.
Emotional lability, another condition associated with stroke, occurs in about twenty percent of stroke patients and causes a patient to switch quickly between emotional highs and lows and to express emotions inappropriately (e.g., an excess of laughing or crying with little or no provocation). While these expressions of emotion usually correspond to the patient's actual emotions, a more severe form of emotional lability causes patients to laugh and cry pathologically, without regard to context or emotion. Some patients show the opposite of what they feel, (e.g., crying when they are happy).
Cognitive deficits resulting from stroke include perceptual disorders, speech problems, dementia, and problems with attention and memory. A stroke sufferer may be perpetually unaware of his or her own disabilities or even the fact that he or she has suffered a stroke.
A number of treatments are available to prevent stroke. However, the options for treating post-stroke disorders and for functional recovery following stroke are limited.